Portable keyboard



FIG. 1 is a perspective view of an embodiment of a design for a portable keyboard;

FIG. 2 is a top view of the portable keyboard shown in FIG. 1;

FIG. 3 is a bottom view of the portable keyboard shown in FIG. 1;

FIG. 4 is a front edge view of the portable keyboard shown in FIG. 1;

FIG. 5 is a rear edge view of the portable keyboard shown in FIG. 1;

FIG. 6 is a left edge view of the portable keyboard shown in FIG. 1; and,

FIG. 7 is a right edge view of the portable keyboard shown in FIG. 1.

The broken lines in the drawings illustrate portions of a portable keyboard which form no part of the claimed design. 

CLAIM The ornamental design for a portable keyboard, as shown and described. 